One of the components of the mass spectrometry workgroup mission is to provide other groups within LMB and NIEHS access to mass spectrometric analyses on a service basis. The workgroup provides the following services on an ongoing basis: 1) low and high resolution electron impact (EI) mass spectra; 2) low and high resolution chemical ionization (CI) mass spectra; 3) negative ion chemical ionization (NICI) mass spectra: 4) gas chromatography/mass spectrometry (GC/MS) in conjunction with EI, CI and NICI MS; 5) thermospray (TSP) liquid chromatography/mass spectrometry (LC/MS) in conjunction with CI and NICI MS; 6) fast atom bombardment (FAB) under both positive and negative ion conditions; 7) continuous flow FAB/MS and FAB/MS/MS under both positive and negative ion conditions; and 8) tandem MS in combination with positive and negative ion FAB, EI and CI MS. During the past year approximately 691 analyses have been performed on a service basis (not including collaborative work).